Adding NIPS as an intermediate step before amniocentesis after high-risk initial results struck best balance between costs, aneuploidy detection.

Adding non-invasive prenatal genetic screening (NIPS) for fetal abnormalities to the blood tests and amniocentesis currently used for prenatal testing is more cost-effective than the current system, researchers from Université Laval in Quebec reported at the American Society of Human Genetics 2016 annual meeting in Vancouver last month.

The researchers used a computer simulation based on 113,000 pregnancies in Quebec in 2014 to compare the cost-effectiveness of 13 screening strategies for aneuploidies: six current prenatal testing strategies, one for universal NIPS, and six incorporating NIPS as contingent test.

They then created decision trees based on real-world factors, such as families opting out of screening and loss to follow up, to determine what parents would have done for each pregnancy in the real world. Next, they assigned a cost to each procedure and computed the total cost to the healthcare system for each protocol.

The researchers divided this number by the number of Down syndrome cases detected to calculate the cost per case detected and the incremental cost per case (ICER) detected (the extra cost per case detected that would not have been detected without NIPS). They ran each simulation 1,000 times to confirm the accuracy.

At a baseline risk cut-off of 1:300, a risk cut-off of 1:30 (contingent and sequential), and a cost of $795 per NIPS sample, the authors found that using NIPS as contingent test cost less and had fewer procedure-related losses than current options. However, it detected 10% to 13% fewer aneuploidy cases.

While the universal first-line NIPS detected more aneuploidy cases with fewer procedure-related losses, it was much more expensive than other screening strategies.

Among the 13 options tested, the researchers concluded that the Serum Integrated NIPS is the most cost-effective option, followed by the Serum Integrated. Serum Integrated NIPS involves a blood test at 10 weeks’ gestation, followed by a second blood test at 12-14 weeks. For blood test results indicating high risk (about 1 in 300), NIPS is performed within a week, and when NIPS confirms there is a risk, amniocentesis is performed and a diagnosis is made as appropriate. This approach would reduce the number of amniocentesis procedures performed by about 90 percent, according to the authors.

The next step, said lead author Francois Rousseau, MD, MSc, a professor of medicine at the Université Laval, is to perform a budget impact analysis and conduct a pilot test or clinical trial of the one or two most promising options to see how these results play out in healthcare systems.